Optical modulation device and projector

ABSTRACT

An optical modulation device is presented having a distance Wp from the end of an opposite substrate to the inner peripheral edge of a cover portion in a frame being set to be smaller than the distance W 1  from the end of the opposite substrate to the inner peripheral edge of a first light-shielding portion (Wp&lt;W 1 ). Therefore, there is no fear that incident light from outside of the inner peripheral edge of the cover portion may be blocked by the cover portion, so that incident light may reliably enter the entire image area. This arrangement makes it possible to prevent the peripheral portion of a projection image from becoming dark, and thereby improve the quality of the projection image.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an optical modulation device having anelectrooptical device, such as a liquid crystal panel, and to aprojection display device using this optical modulation device.

2. Description of the Related Art

A liquid crystal panel that serves as an electrooptical device for usein a projection display device generally comprises an active matrixsubstrate having pixel electrodes and pixel switching elements, anopposite substrate having opposite electrodes, and liquid crystalinterposed between the active matrix substrate and the oppositesubstrate. The liquid crystal is filled in a region partitioned by asealing layer out of the space between the active matrix substrate andthe opposite substrate, and the alignment state thereof is controlledpixel by pixel between the active matrix substrate and the oppositesubstrate.

Therefore, in a projection display device using the liquid crystal panelhaving such a structure as an optical modulation device, light emittedfrom a light source is collected and guided to the liquid crystal panelby a light-collecting optical system, and this light is opticallymodulated by the liquid crystal, whereby a predetermined image isenlarged and projected onto a projection plane, such as a screen, by aprojection lens.

The liquid crystal panel structured as mentioned above is usually heldby a light-shielding holding member having an open portion correspondingto an image area. In general, the image area is outlined by a lightshielding portion of Cr (chrome) that is formed between the activematrix substrate and the opposite substrate to define the periphery.

On the light-incident side of the liquid crystal panel, however, since acover portion that forms a peripheral edge of the open portion of theholding member faces the light-incident surface of the liquid crystalpanel (opposite substrate) and overlaps with the light-shielding portionin a planar manner, light that is incident from the outside of the innerperipheral edge of the cover portion is blocked by the cover portiondepending on the incident angle. Therefore, the peripheral portion of aprojection image becomes dark, and this may deteriorate the quality ofthe projection image.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an optical modulationdevice that is able to improve the quality of a projection image, and aprojection display device using this optical modulation device.

An optical modulation device of the present invention includes anelectrooptical device having a first light-transmissive substratedisposed on the light-incident side, a second light-transmissivesubstrate disposed on the light-emitting side, liquid crystal interposedbetween opposing surfaces of these first and second light-transmissivesubstrates, and a driving circuit disposed at the peripheral edge of alight-incident surface of the second light-transmissive substrate, and aholding member for holding the electrooptical device, wherein a firstlight-shielding portion for defining an image area is formed between thefirst and second light-transmissive substrates in the electroopticaldevice, a cover portion for covering the peripheral edge of alight-incident surface of the first light-transmissive substrate isformed in the holding member, and Wp and W1 are set in a relationshipthat is expressed by the following equation (1):

Wp<W 1  (1)

where Wp is the distance from the end of the first light-transmissivesubstrate to the inner peripheral edge of the cover portion in theholding member, and W1 is the distance from the end of the firstlight-transmissive substrate to the inner peripheral edge of the firstlight-shielding portion.

Herein, “the inner peripheral edge of the cover portion” means a part ofthe cover portion that projects toward the image area to the largestdegree and that is most apart from the light-incident surface of thefirst light-transmissive substrate. Furthermore, “the distance from theend of the first light-transmissive substrate” means the distance alongthe in-plane direction of the first light-transmissive substrate.

In the present invention configured like this, since the distance Wpfrom the end of the first light-transmissive substrate to the innerperipheral edge of the cover portion is set to be smaller than thedistance W1 from the end of the first light-transmissive substrate tothe inner peripheral edge of the first light-shielding portion, there isno fear that the inner peripheral edge of the cover portion may projectinto the image area beyond the first light-shielding portion. Sinceincident light that is incident from the outside of the inner peripheraledge of the cover portion reliably enters the entire image area withoutbeing blocked by the cover portion, the peripheral portion of aprojection image does not become dark, and the quality of the projectionimage is thereby improved.

In the optical modulation device of the present invention, when theincident angle of incident light, which is incident from the inside ofthe inner peripheral edge of the cover portion, of light that isincident on the electrooptical device, is θi, the incident angle ofincident light, which is incident from the outside of the innerperipheral edge of the cover portion, is θo, the distance from the innerperipheral edge of the cover portion to the light-incident surface ofthe first light-transmissive substrate is dp, the thickness of the firstlight-transmissive substrate is d1, the distance from the end of thefirst light-transmissive substrate to the outer peripheral edge of thefirst light-shielding portion is W1′, and the refractive index of thefirst light-transmissive substrate is n1, it is preferable to set Wp,W1, and W1′ in a relationship expressed by the following equation (2).$\begin{matrix}{{{W1}^{\prime} + {{dp}\quad \tan \quad \theta \quad i} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W1} - {{dp}\quad \tan \quad \theta \quad o} - {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}}}} & (2)\end{matrix}$

When the first light-transmissive substrate and the secondlight-transmissive substrate are bonded with a sealing material of anultraviolet-curing type, there is a need to leave a light-transmissiveportion of the first light-transmissive substrate outside the firstlight-shielding portion. Since the first light-transmissive substratehas the thickness d1, incident light that is incident from the inside ofthe inner peripheral edge of the cover portion is, in some cases, notentirely blocked by the cover portion of the holding member according tothe incident angle, passes through the light-transmissive portion of thefirst light-transmissive substrate, and leaks from the outer peripheraledge of the first light-shielding portion. For this reason, the leakingincident light impinges on a driving circuit that is disposed on theperiphery of the second light-transmissive substrate, thereby causing amalfunction of the driving circuit. When the distance Wp is set withinthe range given by the equation (2), however, there is no fear that thequality of a projection image may be deteriorated by incident light thatis incident from the outside at the incident angle θo. Moreover, thereis no fear that incident light incident from the inside at the incidentangle θi may leak from the outer peripheral edge of the firstlight-shielding portion, and that the light may be applied onto thedriving circuit disposed on the periphery of the secondlight-transmissive substrate. Therefore, even when a light-transmissiveportion is formed outside the first light-shielding portion, the drivingcircuit is prevented from malfunctioning.

Furthermore, in the optical modulation device of the present invention,it is preferable to form a third light-transmissive substrate betweenthe first light-transmissive substrate and the cover portion.Furthermore, when the incident angle of incident light incident from theinside of the inner peripheral edge of the cover portion, of lightincident on the electrooptical device, is θi, the incident angle ofincident light incident from the outside of the inner peripheral edge ofthe cover portion is θo, the distance from the inner peripheral edge ofthe cover portion to a light-incident surface of the thirdlight-transmissive substrate is dp′, the thickness of the firstlight-transmissive substrate is d1, the thickness of the thirdlight-transmissive substrate is d2, the distance from the end of thefirst light-transmissive substrate to the outer peripheral edge of thefirst light-shielding portion is W1′, and the refractive indices of thefirst light-transmissive substrate and the third light-transmissivesubstrate are n1 and n2 respectively, it is preferable to set Wp, W1,and W1′ in a relationship expressed by the following equation (3).$\begin{matrix}{{{W1}^{\prime} + {{dp}^{\prime}\tan \quad \theta \quad i} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}} + {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W1} - {{dp}^{\prime}\tan \quad \theta \quad o} - {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}} - {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}}}} & (3)\end{matrix}$

In such a case, the third light-transmissive substrate serves as adustproof light-transmissive substrate, so that the light-incidentsurface of the first light-transmissive substrate is protected from dustand flaws, and there is no fear that such dust and flaws will beenlarged in projection.

In this case, it is preferable to form a second light-shielding portionbetween the third light-transmissive substrate and the firstlight-transmissive substrate and to set Wp, W1, and W2 in a relationshipexpressed by the following equation (4):

Wp<W 2 <W 1  (4)

where W2 is the distance from the end of the first light-transmissivesubstrate to the inner peripheral edge of the second light-shieldingportion.

In such a case, since the second light-shielding portion is formedbetween the first light-transmissive substrate and the thirdlight-transmissive substrate and the distance W2 from the end of thefirst light-transmissive substrate to the inner peripheral edge of thesecond light-shielding portion is set within the range given by theequation (4), light that is incident from the inside and passes throughthe inner peripheral edge of the cover portion is blocked by the secondlight-shielding portion. Therefore, in the case of the firstlight-shielding portion, there is no need to consider such incidentlight. Regarding light that is incident from the inside, considerationshould be given to incident light that passes through the innerperipheral edge of the second light-shielding portion, so that thedistance W1′ from the end of the first light-transmissive substrate tothe outer peripheral edge of the first light-shielding portion is set tobe larger.

When the distance from the end of the first light-transmissive substrateto the outer peripheral edge of the second light-shielding portion isW2′, Wp, W1, W1′, W2, and W2′ may be set in a relationship expressed bythe following equations (5) and (6). $\begin{matrix}{{{W2}^{\prime} + {{dp}^{\prime}\tan \quad \theta \quad i} + {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W2} - {{dp}^{\prime}\tan \quad \theta \quad o} - {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}}}} & (5) \\{{{W1}^{\prime} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {W2} \leq {{W1} - {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}}}} & (6)\end{matrix}$

In such a case, the distance W2′ from the end of the firstlight-transmissive substrate to the outer peripheral edge of the secondlight-shielding portion can be set based on a positional relationship tothe distance Wp of the cover portion so that light incident from theinside does not leak from the outer peripheral edge of the secondlight-shielding portion. Therefore, under certain circumstances, thesecond light-shielding portion may be formed over a wide area from theend of the first light-transmissive substrate by setting W2′ to be atzero, whereby the incident light from the inside is less prone to leaktoward the driving circuit.

When an air layer having a thickness d3 is formed between the firstlight-transmissive substrate and the third light-transmissive substrate,and a second light-shielding portion is formed on the light-emittingsurface of the third light-transmissive substrate, it is preferable toset Wp, W1, W1′, W2, and W2′ in a relationship expressed by thefollowing equations (7) and (8). $\begin{matrix}{{{W2}^{\prime} + {{dp}^{\prime}\tan \quad \theta \quad i} + {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W2} - {{dp}^{\prime}\tan \quad \theta \quad o} - {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}}}} & (7) \\{{{W1}^{\prime} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}} + {{d3}\quad \tan \quad \theta \quad i}} \leq {W2} \leq {{W1} - {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}} - {{d3}\quad \tan \quad \theta \quad o}}} & (8)\end{matrix}$

In such a case, since the air layer is formed between the firstlight-transmissive substrate and the third light-transmissive substrate,heat that is generated in the third light-transmissive substrate is lessprone to be transmitted toward the electrooptical device, compared witha case in which the air layer is not formed.

In contrast, when the second light-shielding portion is formed on thelight-incident surface of the first light-transmissive substrate, it ispreferable to set Wp, W1, W1′, W2, and W2′ in a relationship expressedby the following equations (9) and (10). $\begin{matrix}{{{W2}^{\prime} + {\left( {{dp}^{\prime} + {d3}} \right)\tan \quad \theta \quad i} + {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W2} - {\left( {{dp}^{\prime} + {d3}} \right)\tan \quad \theta \quad o} - {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}}}} & (9) \\{{{W1}^{\prime} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {W2} \leq {{W1} - {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}}}} & (10)\end{matrix}$

In this case, the aforesaid effect produced by forming the air layer isalso obtained.

On the other hand, a projection display device of the present inventionincludes a light source, the optical modulation device mentioned above,and a projection lens for projecting light modulated by the opticalmodulation device. It is possible to provide a projection display devicein which the above-mentioned effects are similarly obtained.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the external appearance of aprojection display device that is equipped with an optical modulationdevice according to a first embodiment of the present invention.

FIG. 2 is a plan view of an optical system in the projection displaydevice.

FIG. 3 is a plan view of an electrooptical device that constitutes theoptical modulation device.

FIG. 4A is a cross-sectional view taken along line H-H′ in FIG. 3, andFIG. 4B is an enlarged view showing the principal part of FIG. 4A.

FIG. 5A is a block diagram of a second light-transmissive substrate usedin the electrooptical device, and FIG. 5B is an enlarged block diagramof one of pixels arranged in a matrix on the second light-transmissivesubstrate.

FIG. 6 is another enlarged view showing the principal part of theoptical modulation device.

FIG. 7 is an enlarged view showing the principal part of an opticalmodulation device according to a second embodiment of the presentinvention.

FIG. 8 is an enlarged view showing the principal part of an opticalmodulation device according to a third embodiment of the presentinvention.

FIG. 9 is an enlarged view showing the principal part of an opticalmodulation device according to a fourth embodiment of the presentinvention.

FIG. 10 is an enlarged view showing the principal part of an opticalmodulation device according to a fifth embodiment of the presentinvention.

FIG. 11 is an enlarged view showing a variation of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention will be described below withreference to the drawings.

1. First Embodiment

A. Structure of Principal Part of Projection Display Device

A projection display device according to this embodiment of the presentinvention is of a type that separates a light beam emitted from a lightsource into color beams of red R, green G, and blue B, modulates thesecolor beams by liquid crystal light valves according to imageinformation, synthesizes the modulated color beams, and magnifies anddisplays the synthesized beams onto a screen via a projection lens.

FIG. 1 shows the external appearance of a projection display device 1 ofsuch a type. As shown in this figure, the projection display device 1has an outer casing 2 shaped like a rectangular parallelepiped. Theouter casing 2 is basically composed of an upper casing 3, a lowercasing 4, and a front casing 5 that defines the front surface of thedevice. A leading portion of a projection lens unit 49 projects from thecenter of the front casing 5.

Inside such an outer casing 2 of the projection display device 1, anoptical unit 10 shown in FIG. 2 is mounted.

This optical unit 10 generally comprises an illumination optical system15 for emitting illumination light, a color separation optical system 20for separating a light beam emitted from the illumination optical system15 into color beams R, G, and B of red, green, and blue, three liquidcrystal light valves 30R, 30G, and 30B for modulating the color beams, aprism unit 42 formed of a dichroic prism that serves as a colorsynthesizing optical system for synthesizing the modulated color beams,and the projection lens unit 49 for magnifying and projecting thesynthesized beams onto a screen.

The illumination optical system 15 includes a light-source lamp 11, twolens plates 12 and 14, a polarization conversion element 16, asuperimposing lens 17, and a reflecting mirror 18.

Used as the light-source lamp 11 are a halogen lamp, a metal halidelamp, a xenon lamp, and the like.

The first lens plate 12 has a plurality of small lenses. A light beamemitted from the light-source lamp 11 is separated into a plurality ofpartial beams by these small lenses. Then, the partial beams aresuperimposed onto the liquid crystal light valves 30R, 30G, and 30B viathe superimposing lens 17. Therefore, the liquid crystal light valves30R, 30G, and 30B are illuminated at almost uniform illuminance.

The second lens plate 14 has a plurality of small lenses, similar to thefirst lens plate 12. The center optical paths of the partial beamsemitted from the first lens plate 12 are aligned in parallel with thelight-source optical axis by these small lenses. When a light beamemitted from the light-source lamp 11 is light that is parallel to thelight-source optical axis, the center optical path of a partial beamemitted from the first lens plate 12 is also in parallel with thelight-source optical axis. Therefore, when light beams emitted from thelight-source lamp 11 have high parallelism, the second lens plate 14 maybe omitted.

The polarization conversion element 16 includes a polarization beamseparation element, in which a plurality of polarization beam separationfilms and a plurality of reflecting films are alternately arrangednearly in parallel, and a half-wave plate (not shown). Light, which iscollected on the polarization beam separation films via the small lensesin the first lens plate 12 and the second lens plate 14, is separatedinto p-polarized light and s-polarized light. P-polarized light that haspassed through the polarization beam separation film is converted intos-polarized light by the half-wave plate. On the other hand, s-polarizedlight that has been reflected by the polarization beam separation filmis reflected by the reflecting film, and emitted in almost the samedirection as that of the light that has been converted into s-polarizedlight. That is, light emitted from the light-source lamp 11 andpolarized in random directions is unified into one type of polarizedlight by the polarization conversion element 16.

The superimposing lens 17 superimposes, on the liquid crystal lightvalves 30R, 30G, and 30B, a plurality of partial beams that areseparated by the first lens plate 12 and then unified into one type ofpolarized light by the polarization conversion element 16.

The reflecting mirror 18 bends the optical path of illumination lighttoward the front of the device.

In the color separation optical system 20, a red and green reflectingdichroic mirror 22, a green reflecting dichroic mirror 24, and areflecting mirror 26 are arranged. Out of the light beams emitted fromthe illumination optical system 15, via illumination optical system 15,firstly a red beam R and a green beam G are perpendicularly reflected bythe red and green reflecting dichroic mirror 22, and travel toward thegreen reflecting dichroic mirror 24. A blue beam B passes through thisred and green reflecting dichroic mirror 22, and then is perpendicularlyreflected by the reflecting mirror 26 disposed behind, and emerges froman emitting portion for the blue beam toward the prism unit 42. Next,only the green beam G of the red and green beams R and G that have beenreflected by the red and green reflecting dichroic mirror 22 isperpendicularly reflected by the green reflecting dichroic mirror 24,and emitted from an emitting portion for the green light toward theprism unit 42. Furthermore, the red beam R that has passed through thegreen reflecting dichroic mirror 24 is emitted from an emitting portionfor the red beam toward a light guide system 44. Light-collecting lenses45, 28, and 29 are disposed on the emitting sides of the colorseparation optical system 20 for the color beams.

The blue and green beams B and G collected by the light-collectinglenses 28 and 29 enter the liquid crystal light valves 30B and 30G,where they are modulated and given image information correspondingthereto. That is, these liquid crystal light valves 30R and 30G aresubjected to switching control according to image information by adriving system that is not shown, so that the color beams passingtherethrough are modulated. As such a driving system, a known type ofsystem may be used unchanged.

On the other hand, the red beam R is guided to the liquid crystal lightvalve 30R via the light guide system 44, where it undergoes similarmodulation according to image information. The light guide system 44includes an incident-side light-collecting lens 45, an incident-sidereflecting mirror 46, an emitting-side reflecting mirror 47, anintermediate lens 48 interposed therebetween, and an emitting-sidelight-collecting lens, and has a function of avoiding light loss of redlight in the optical path. As the liquid crystal light valves 30R, 30B,and 30G in this embodiment, for example, liquid crystal light valvesusing a polysilicon TFT as a switching element may be used.

The color beams modulated through the liquid crystal light valves 30R,30G, and 30B enter the prism unit 42, where they are synthesized. Theresynthesized color image is magnified and projected onto a screen,disposed at a predetermined position, via the projection lens unit 49.

B. Structure of Optical Modulation Device

These liquid crystal light valves 30R, 30G, and 30B have a combinationof an optical modulation device 50 shown in FIGS. 3 and 4A-B, whichincludes a liquid crystal panel 30 serving as an electrooptical deviceand a holding member 90 (shown by a double-dotted chain line in FIG. 3)for holding the liquid crystal panel 30, and polarizers disposed on bothsides of the liquid crystal panel 30, which are not shown.

In FIGS. 3 and 4A-B, the liquid crystal panel 30 in the opticalmodulation device 50 includes an active matrix substrate 300 (secondlight-transmissive substrate), and a opposite substrate 400 (firstlight-transmissive substrate) having a opposite electrode 31. The activematrix substrate 300 and the opposite substrate 400 are bonded with apredetermined spacing (cell gap) therebetween with a sealing material 80containing a gap-forming material, and the space between thesesubstrates contains liquid crystal LC that serves as an electroopticalsubstance and is sealed up. As the sealing material 80, various kinds ofultraviolet-curing resins may be used. As the gap-forming material,inorganic or organic fibers or spheres of about 2 μm to 10 μm may beused.

The opposite substrate 400 is smaller than the active matrix substrate300, and is bonded so that the peripheral portion of the active matrixsubstrate 300 appears outside the outer peripheral edge of the oppositesubstrate 400. A data-line driving circuit 60 and scanning-line drivingcircuits 70 that are composed of long and narrow bare chip ICs (driverICs) and input and output terminals 81 of the active matrix substrate300 are mounted on the light-incident side of the peripheral portion. Aflexible printed wire board (not shown) is electrically connected to theinput and output terminals 81 of these circuits 60 and 70 that arepositioned outside the opposite substrate 400.

The sealing material 80 is partially discontinuous, and thisdiscontinuous portion forms a liquid crystal injection port 83. For thisreason, when the pressure of a inside region of the sealing material 80is reduced after the opposite substrate 400 and the active matrixsubstrate 300 are bonded to each other, the liquid crystal LC can beinjected from the liquid crystal injection port 83 at a reducedpressure. After the liquid crystal LC is sealed therein, the liquidcrystal injection port 83 is closed with a sealant 82. On the oppositesubstrate 400, a first light-shielding portion 31 is formed at theinside of the sealing material 80 (inside in the in-plane direction).This first light-shielding portion 31 defines an image area on theliquid crystal panel 30.

The structure of the active matrix substrate 300 used for such a liquidcrystal panel 30, on which the driver ICs (the data-line driving circuit60 and the scanning-line driving circuits 70) are mounted, is shown inFIG. 5A as a block diagram.

As shown in FIG. 5A, a plurality of pixels “px” are formed in a matrixon the active matrix substrate 300 by scanning lines “gate” and aplurality of data lines “sig.” In a region of each pixel px, a thin-filmtransistor TFT for pixel switching is formed to be connected to ascanning line “gate” and a data line “sig.”, as shown in FIG. 5B in anenlarged view. A drain electrode of this thin-film transistor TFT is apixel electrode in which a liquid crystal cell is formed by placingliquid crystal LC between the opposite electrode (FIG. 4B) of theaforesaid opposite substrate 400 and the pixel px. In the liquid crystalcell, a hold capacitor “cap” is formed by using the scanning line “gate”and a capacity line (not shown).

In the active matrix substrate 300, the data-line driving circuit 60disposed on the periphery of the active matrix substrate 300 is anintegrated circuit for supplying a plurality of data lines “sig” with animage signal, and the scanning-line driving circuits 70 are integratedcircuits that include a shift register 71 for supplying a plurality ofscanning lines “gate” with a scanning signal for image selection, and abuffer. The data-line driving circuit 60 includes an X-side shiftregister 61 to be supplied with a clock signal, a sample-and-holdcircuit 62 for operating according to a signal output from the X-sideshift register 61, and six image signal lines 63 corresponding to imagesignals that are expanded to six phases. For this reason, thesample-and-hold circuit 62 can operate according to a signal output fromthe X-side shift register 61, fetch an image signal supplied via theimage signal line 63 into a data line “sig” at a predetermined timing,and supply the image signal to each pixel px.

On the other hand, referring again to FIG. 4A, the holding member 90 ofthe optical modulation device 50 includes a frame 91 disposed on thelight-incident side of the liquid crystal panel 30, and a hook 92 thatis disposed on the light-emitting side of the liquid crystal panel 30and is held by projections 91A of the frame 91. The frame 91 and thehook 92 hold the liquid crystal panel 30 therebetween. The frame 91 andthe hook 92 have open portions 93 and 94 corresponding to the image areaof the liquid crystal panel 30, respectively. In particular, a partaround the open portion 93 of the frame 91 is formed by a cover portion95 that faces a light-incident surface 401 of the opposite substrate400. In this embodiment, as shown in FIG. 6, the cover portion 95 isshaped like a wedge having an acute tip that approaches the oppositesubstrate 400 according to be nearer to the inside (toward the imagearea).

C. Positional Relationship between Cover Portion and FirstLight-Shielding Portion in Optical Modulation Device

In FIG. 6, the distance Wp from the end of the opposite substrate 400 tothe inner peripheral edge of the cover portion 95 in the frame 91 (thedistance in the in-plane direction of the opposite substrate 400) is setto be smaller than the distance W1 from the end of the oppositesubstrate 400 to the inner peripheral edge of the first light-shieldingportion 31, as expressed by the equation (1) mentioned above.

More specifically, the distance Wp is set as follows.

That is, when the incident angle of incident light, which is incidentfrom the inside of the inner peripheral edge of the cover portion 95, oflight that is incident on the liquid crystal panel 30, is θi, theincident angle of incident light, which is incident from the outside ofthe inner peripheral edge, is θo, the distance between the innerperipheral edge of the cover portion 95 and the light-incident surface401 of the opposite substrate 400 is dp, the thickness of the oppositesubstrate 400 is d1, the distance from the end of the opposite substrate400 to the outer peripheral edge of the first light-shielding portion 31is W1′, and the refractive index of the opposite substrate 400 is n1,the distance Wp satisfies the following equation (11) so that the coverportion 95 does not block incident light from the outside, and satisfiesthe following equation (12), and also so that incident light from theinside does not leak from the outer peripheral edge of the firstlight-shielding portion 31. Therefore, the distance Wp satisfies anequation (13).

Wp≦W 1 −dp tan θo−d 1 tan θo 1  (11)

Wp≧W 1′+dp tan θi+d 1 tan θi 1  (12)

∴W 1′+dp tan θi+d 1 tan θi 1≦Wp≦W 1 −dp tan θo−d 1 tan θo 1  (13)

An equation (16) is obtained from the following general formulae (14)and (15). Similarly, an equation (19) is obtained from formulae (17) and(18).

sin² θo 1+cos² θo 1=1  (14) $\begin{matrix}{{{\tan^{2}\theta \quad {o1}} + 1} = \frac{1}{\cos^{2}\theta \quad {o1}}} & (15) \\{{\therefore{\tan^{2}\theta \quad {o1}}} = {{\frac{1}{\cos^{2}\theta \quad {o1}} - 1} = \frac{\sin^{2}\theta \quad {o1}}{1 - {\sin^{2}\theta \quad {o1}}}}} & (16) \\{{{\sin^{2}\theta \quad {i1}} + {\cos^{2}\theta \quad {i1}}} = 1} & (17) \\{{{\tan^{2}\theta \quad {i1}} + 1} = \frac{1}{\cos^{2}\theta \quad {i1}}} & (18) \\{{\therefore{\tan^{2}\theta \quad {i1}}} = {{\frac{1}{\cos^{2}\theta \quad {i1}} - 1} = \frac{\sin^{2}\theta \quad {i1}}{1 - {\sin^{2}\theta \quad {i1}}}}} & (19)\end{matrix}$

Furthermore, equations (22) and (23) are obtained from the followingother general formulae (20) and (21).

sin θo=n 1 sin o 1  (20)

sin θi=n 1 sin θi 1  (21)

$\begin{matrix}{{\sin^{2}\theta \quad {o1}} = \frac{\sin^{2}\theta \quad o}{{n1}^{2}}} & (22) \\{{\sin^{2}\quad \theta \quad {i1}} = \frac{\sin^{2}\theta \quad i}{{n1}^{2}}} & (23)\end{matrix}$

The following equation (24) is obtained by substituting the equation(22) for the aforesaid equation (16) because −90°<θo<90° and−90°<θi<90°. An equation (25) is obtained by substituting the equation(23) for the aforesaid equation (19). θo and θi are positive from thedotted chain line in the figure in the directions of the arrows,respectively. $\begin{matrix}{{\tan \quad \theta \quad {o1}} = \frac{\sin \quad \theta \quad o}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}} & (24) \\{{\tan \quad \theta \quad {i1}} = \frac{\sin \quad \theta \quad i}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}} & (25)\end{matrix}$

By substituting these equations (24) and (25) for the equation (13), theaforesaid equation (2) is obtained. Therefore, the distance Wp is setwithin the range given by the equation (2).

This embodiment provides the following advantages.

Since the distance Wp from the end of the opposite substrate 400 to theinner peripheral edge of the cover portion 95 in the frame 91 is set tobe smaller than the distance W1 from the end of the opposite substrate400 to the inner peripheral edge of the first light-shielding portion31, as expressed by the equation (1), it is possible to prevent theinner peripheral edge of the cover portion 95 from projecting into theimage area beyond the first light-shielding portion 31. Since there isno fear that light incident from the outside of the inner peripheraledge of the cover portion 95 will be blocked by the cover portion 95,incident light can enter the entire image area, thereby preventing theperipheral portion of a projection image from becoming dark, andimproving the quality of the projection image.

More specifically, since the distance Wp is set within the range givenby the equation (2), there is no fear that incident light, which isincident from the outside at the incident angle θo, will be blocked bythe frame 91. In addition, it is possible to prevent incident light,which is incident from the inside at the incident angle θi, from leakingfrom the outer peripheral edge of the first light-shielding portion 31,and to prevent light from being radiated onto the circuits 60 and 70disposed on the periphery of the active matrix substrate 300, wherebymalfunctions of these circuits can be avoided. With this, it is possibleto prevent display shadows of the circuits 60 and 70 from beingproduced.

According to the equation (2), since there is no need to continuouslyform the first light-shielding portion 31 from the end of the oppositesubstrate 400 toward the image area, a light-transmissive portioncorresponding to the distance W1′ can be ensured between the end of theopposite substrate 400 and the outer peripheral edge of the firstlight-shielding portion 31. For this reason, it is possible to applyultraviolet rays onto the sealing material 80 of the ultraviolet-curingtype by using the light-transmissive portion, and to thereby bond theactive matrix substrate 300 and the opposite substrate 400 morereliably.

2. Second Embodiment

FIG. 7 shows a positional relationship between a cover portion 95 and afirst light-shielding portion 31 according to a second embodiment.

In this embodiment, a dustproof light-transmissive substrate 500 isdisposed as a third light-transmissive substrate on the light-incidentside of a opposite substrate 400, thereby protecting a light-incidentsurface 401 of the opposite substrate 400 from dust and flaws. The otherstructures are the same as those of the first embodiment.

In this embodiment, the distance Wp from the end of the oppositesubstrate 400 to the inner peripheral edge of the cover portion 95 of aframe 91 is set as follows.

That is, when the distance between the inner peripheral edge of thecover portion 95 and a light-incident surface 501 of the dustprooflight-transmissive substrate 500 is dp′, the thickness of the dustprooflight-transmissive substrate 500 is d2, and the refractive index thereofis n2, the distance Wp satisfies the following equations (26) and (27),and therefore, satisfies an equation (28), in a manner similar to thefirst embodiment.

Wp≦W 1 −dp′ tan θo−d 1 tan θo 1 −d 2 tan θo 2  (26)

Wp≧W 1′+dp′ tan θi+d 1 tan θi 1 +d 2 tan θi 2  (27)

∴W 1′+dp′ tan θi+d 1 tan θi 1 +d 2 tan θi 2 ≦Wp≦W 1 −dp′ tan θo−d 1 tanθo 2 tan θo 2  (28)

Similar to the first embodiment, the following equations (29) to (32)are obtained from the general formulae: $\begin{matrix}{{\tan^{2}\theta \quad {o2}} = \frac{\sin^{2}\theta \quad {o2}}{1 - {\sin^{2}\theta \quad {o2}}}} & (29) \\{{\tan^{2}\theta \quad {i2}} = \frac{\sin^{2}\theta \quad {i2}}{1 - {\sin^{2}\theta \quad {i2}}}} & (30) \\{{\sin^{2}\theta \quad {o2}} = \frac{\sin^{2}\theta \quad o}{{n2}^{2}}} & (31) \\{{\sin^{2}\theta \quad {i2}} = \frac{\sin^{2}\theta \quad i}{{n2}^{2}}} & (32)\end{matrix}$

Since −90°<θo<90° and −90°<θi<90°, the following equation (33) isobtained by substituting the equation (31) for the equation (29), and anequation (34) is obtained by substituting the equation (32) for theequation (30). $\begin{matrix}{{\tan \quad \theta \quad {o2}} = \frac{\sin \quad \theta \quad o}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}} & (33) \\{{\tan \quad \theta \quad {i2}} = \frac{\sin \quad \theta \quad i}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}} & (34)\end{matrix}$

By substituting these equations (33) and (34) and the aforesaidequations (24) and (25) for the equation (28), the aforesaid equation(3) is obtained. Therefore, the distance Wp is set within the rangegiven by the equation (3). In some cases, the refractive index n2 of thedustproof light-transmissive substrate 500 is equal to the refractiveindex n1 of the opposite substrate 400.

This embodiment provides the following advantages because of thedustproof light-transmissive substrate 500 as well as the aforementionedadvantages of the first embodiment.

Since the dustproof light-transmissive substrate 500 is disposed on thelight-incident side of the opposite substrate 400, it is possible toprotect the light-incident surface 401 of the opposite substrate 400from dust and flaws, and to prevent the dust and flaws from beingmagnified and projected onto the projection screen. Moreover, since thelight-incident surface 501 of the dustproof light-transmissive substrate500 is apart from the liquid crystal panel 30, even when there are dustand flaws on the light-incident surface 501 of the dustprooflight-transmissive substrate 500, such dust and flaws are out of focus,and there is no fear that they will be projected to deteriorate displayquality.

3. Third Embodiment

FIG. 8 illustrates a third embodiment.

This embodiment differs from the above second embodiment in that asecond light-shielding portion 32 is formed between a opposite substrate400 and a dustproof light-transmissive substrate 500. Other structuresare the same as those of the second embodiment.

In this embodiment, a distance W2 from the end of the opposite substrate400 to the inner peripheral edge of the second light-shielding portion32 is set to be larger than the aforesaid Wp and smaller than theaforesaid W1, as expressed by the equation (4) mentioned above.

More specifically, the distance Wp and the distance W2 are set asfollows.

That is, when the distance from the end of the opposite substrate 400 tothe outer peripheral edge of the second light-shielding portion 32 isW2′, Wp satisfies the following equations (35) and (36), and therefore,satisfies an equation (37).

Wp≦W 2 −dp′ tan θo−d 2 tan θo 2  (35)

Wp≧W 2 ′+dp′ tan θi+d 2 tan θi 2  (36)

∴W 2′+dp′ tan θi+d 2 tan θi 2≦Wp≦W 2−dp′ tan θo 2  (37)

The aforesaid equation (5) is obtained by substituting the equations(24), (25), (33), and (34) for the equation (37). Therefore, thedistance Wp is set within the range given by the equation (5).

On the other hand, the distance W2 between the end of the oppositesubstrate 400 and the inner peripheral edge of the secondlight-shielding portion 32 satisfies the following equation (38) so thatincident light from the outside is not blocked with respect to a firstlight-shielding portion 31, and satisfies an equation (39) so thatincident light from the inside does not leak from the outer peripheraledge of the first light-shielding portion 31. Therefore, the distance W2satisfies an equation (40).

W 2 ≦W 1 −d 1 tan θo 1  (38)

W 2 ≧W 1 ′+d 1 tan θi 1  (39)

∴W 1′+d 1 tan θi 1≦W 2≦W 1−d 1 tan θo 1  (40)

By substituting the aforesaid equations (24), (25), (33), and (34) forthe equation (40), the aforesaid equation (6) is obtained, andtherefore, the distance W2 is set within the range given by the equation(6).

This embodiment provides the following advantages as well as theadvantages of the first and second embodiments mentioned above.

Since the second light-shielding portion 32 is formed between theopposite substrate 400 and the dustproof light-transmissive substrate500 and the distance W2 between the end of the opposite substrate 400and the inner peripheral edge of the second light-shielding portion 32is set within the range given by the equation (4), the secondlight-shielding portion 32 can block incident light from the inside thatpasses through the inner end of a cover portion 95. Therefore, in thecase of the first light-shielding portion 31, there is no need toconsider such incident light. Regarding incident light from the inside,consideration should be given to incident light that passes through theinner end of the second light-shielding portion 32. This makes itpossible to increase the distance W1′ between the end of the oppositesubstrate 400 and the outer peripheral edge of the first light-shieldingportion 31. For this reason, more sealing material 80 (FIG. 4(B)) can beused by enlarging the light-transmissive portion of the oppositesubstrate 400, whereby the bonding strength and sealing propertiesbetween the active matrix substrate 300 and the opposite substrate 400can be improved.

As the equations (5) and (6) reveal, the distance W2′ between the end ofthe opposite substrate 400 and the outer peripheral edge of the secondlight-shielding portion 32 is required only to be set, in respect to apositional relationship to the distance Wp of the cover portion 95, sothat light incident from the inside does not leak from the outerperipheral end of the second light-shielding portion 32. Therefore,under certain circumstances, the second light-shielding portion 32 maybe formed over a wide area from the end of the opposite substrate 400 (adouble-dotted chain line in FIG. 8), with W2′ being set at zero. Thismakes it possible to more reliably prevent incident light from theinside from leaking toward the circuits 60 and 70.

4. Fourth Embodiment

FIG. 9 illustrates a fourth embodiment.

This embodiment differs from the aforesaid third embodiment in that anair layer 600 is formed between a opposite substrate 400 and a dustprooflight-transmissive substrate 500 and that a second light-shieldingportion 32 is formed on a light-emitting surface 502 of the dustprooflight-transmissive substrate 500. Other structures are the same as thoseof the third embodiment.

The distance Wp in this embodiment is set within the range given by theaforesaid equation (7) (i.e., the equation (5)), similar to the thirdembodiment.

When the thickness of the air layer 600 is d3, the distance W2 satisfiesthe following equation (41). Since the aforesaid equation (8) isobtained by substituting the equations (24), (25), (33), and (34) forthis equation (41), the distance W2 is set within the range given by theequation (8).

W 1′+d 1 tan θi 1+d 3 tan θi≦W 2≦W 1 −d 1 tan θo 1 −d 3 tan θo  (41)

Such an embodiment can similarly obtain the advantages of the first tothird embodiments, and also provides the following advantages.

Since the air layer 600 is formed between the opposite substrate 400 andthe dustproof light-transmissive substrate 500, heat, which is generatedin the dustproof light-transmissive substrate 500, is less prone to betransmitted to a liquid crystal panel 30, compared with the thirdembodiment in which the air layer 600 is not formed. For this reason, atemperature increase in the liquid crystal panel 30 is small, and thetemperature increase does not occur locally. Therefore, it is possibleto avoid variations in transmittance and deterioration of the liquidcrystal LC that result from the temperature difference.

5. Fifth Embodiment

FIG. 10 illustrates a fifth embodiment.

This embodiment differs from the aforesaid fourth embodiment in that asecond light-shielding portion 32 is formed on a light-incident surface401 of a opposite substrate 400. Other structures are the same as thoseof the fourth embodiment.

The distance Wp in this embodiment satisfies the following equation(42). Since the aforesaid equation (9) is obtained from this equation(42), the distance Wp is set within the range given by the equation (9).

W 2′+(dp′+d 3) tan θo+d 2 tan θo 2≦Wp≦W 2−(dp′+d 3) tan θo−d 2 tan θo2  (42)

The distance W2 is set within the range given by the equation (10)(i.e., the equation (6)), similarly to the third embodiment.

According to this embodiment, advantages similar to those of the fourthembodiment can be obtained.

The present invention is not limited to the embodiments mentioned above.The invention covers other structures that can achieve the object of theinvention, and the following modifications.

For example, while a space is formed between the cover portion 95 of theframe 91 and the light-incident surface 401 of the opposite substrate400 or between the light-incident surfaces 401 and 501 of the dustprooflight-transmissive substrate 500 in the above embodiments, the presentinvention also includes a case in which such a space is not formed. Inthis case, the distance Wp is set on the assumption that dp=dp′=0.

When there is no space between the cover portion 95 and thelight-incident surface 401 and a step portion 95A is formed at the innerperipheral edge of the cover portion 95, as shown in FIG. 11, dp is setto be equal to 0 in the conditional equation relating to incident lightfrom the inside. This also applies to a case in which the dustprooflight-transmissive substrate 500 is used.

In short, the distances dp and dp′ can be regarded as 0, in view of theshape of the cover portion 95 and the distance to the light-incidentsurface.

Furthermore, while the end of the opposite substrate 400 and the end ofthe dustproof light-transmissive substrate 500 are arranged flush witheach other in the second to fifth embodiments (FIGS. 7 to 10), since thedistances Wp, W1, W1′, W2 and W2′ of each of the sections are set withreference to the end of the opposite substrate 400, the end of thedustproof light-transmissive substrate 500 need not be flush with theend of the opposite substrate 400.

Furthermore, while what is called a front projection display device thatperforms projection from the side where a projected object is observedhas been described in the above embodiments, the present invention mayalso be applied to a rear projection display device that performsprojection from the side opposite to the side where a projected objectis observed.

In addition, while what is called a transmissive electrooptical device,in which the light-incident surface and the light-emitting surface aredifferent, has been used in the above embodiments, the electroopticaldevice of the present invention may be of what is called a reflectivetype. In this case, incident light is reflected by an active matrixsubstrate, and emitted from the light-incident surface. Theelectrooptical device may also be devices such as a PLZT panel and adevice using a micro-mirror, other than a liquid crystal panel.

What is claimed is:
 1. An optical modulation device, comprising: anelectrooptical device including a first light-transmissive substratedisposed on a light-incident side, a second light-transmissive substratedisposed on a light-emitting side, a sealing material that adheres firstsurfaces of said first and second light-transmissive substrates with aspace there between, an electrooptical substance interposed between saidfirst surfaces of said first and second light-transmissive substrates,and a driving circuit disposed at a peripheral edge of the first surfaceof said second light-transmissive substrate, and wherein said first andsecond light-transmissive substrates have second surfaces opposite tosaid first surfaces; a holding member that holds said electroopticaldevice and has a cover portion that covers the peripheral edge of thesecond surface of said first light-transmissive substrate; a firstlight-shielding portion formed on said first surface of said firstlight-transmissive substrate; and a relationship between Wp and W1 isexpressed by an equation: Wp<W 1  Wp being the distance from an end ofsaid first light-transmissive substrate to an inner peripheral edge ofsaid cover portion in said holding member, and W1 being the distancefrom the end of said first light-transmissive substrate to an innerperipheral edge of said first light-shielding portion; and arelationship among Wp, W1, and a W1′ is expressed by an equation:${{{W1}^{\prime} + {{dp}\quad \tan \quad \theta \quad i} + {{d1}\frac{\sin \quad \theta \quad i}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W1} - {{dp}\quad \tan \quad \theta \quad o} - {{d1}\frac{\sin \quad \theta \quad o}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}}}},$

 θi being an incident angle of incident light that is incident from theinside of the inner peripheral edge of said cover portion, θo being anincident angle of incident light, that is incident from outside of theinner peripheral edge of said cover portion, dp is a distance from theinner peripheral edge of said cover portion to said second surface ofsaid first light-transmissive substrate, d1 is a thickness of said firstlight-transmissive substrate, W1′ is a distance from the end of saidfirst light-transmissive substrate to an outer peripheral edge of saidfirst light-shielding portion, and n1 is a refractive index of saidfirst light-transmissive substrate.
 2. The optical modulation deviceaccording to claim 1, further comprising a third light-transmissivesubstrate formed between said first light-transmissive substrate andsaid cover portion, and a relationship among Wp, W1, and W1′ isexpressed by an equation:${{W1}^{\prime} + {{dp}^{\prime}\tan \quad \theta \quad i} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}} + {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W1} - {{dp}^{\prime}\tan \quad \theta \quad o} - {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}} - {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}}}$

θi being an incident angle of incident light that is incident frominside of the inner peripheral edge of said cover portion, θo being anincident angle of incident light that is incident from outside of theinner peripheral edge of said cover portion, dp′ is a distance from theinner peripheral edge of said cover portion to a light-incident surfaceof said third light-transmissive substrate, d1 is a thickness of saidfirst light-transmissive substrate, d2 is a thickness of said thirdlight-transmissive substrate, W1′ is a distance from the end of saidfirst light-transmissive substrate to an outer peripheral edge of saidfirst light-shielding portion, and n1 and n2 are refractive indices ofsaid first light-transmissive substrate and said thirdlight-transmissive substrate.
 3. The optical modulation device accordingto claim 2, further comprising a second light-shielding portion formedbetween said third light-transmissive substrate and said firstlight-transmissive substrate, and a relationship among Wp, W1, and W2 isexpressed by an equation: Wp<W2<W1 where W2 is a distance from the endof said first light-transmissive substrate to an inner peripheral edgeof said second light-shielding portion.
 4. The optical modulation deviceaccording to claim 3, a relationship among Wp, W1, W1′, W2, and W2′being expressed by equations: $\begin{matrix}{{{W2}^{\prime} + {{dp}^{\prime}\tan \quad \theta \quad i} + {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W2} - {{dp}^{\prime}\tan \quad \theta \quad o} - {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}}}} \\{{{W1}^{\prime} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {W2} \leq {{W1} - {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}}}}\end{matrix}$

W2′ being the distance from the end of said first light-transmissivesubstrate to an outer peripheral edge of said second light-shieldingportion.
 5. The optical modulation device according to claim 4, furthercomprising an air layer having a thickness d3 formed between said firstlight-transmissive substrate and said third light-transmissivesubstrate, said second light-shielding portion being formed on alight-emitting surface of said third light-transmissive substrate, and arelationship among Wp, W1, W1′, W2, and W2′ is expressed by equations:$\begin{matrix}{{{W2}^{\prime} + {{dp}^{\prime}\tan \quad \theta \quad i} + {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W2} - {{dp}^{\prime}\tan \quad \theta \quad o} - {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}}}} \\{{{W1}^{\prime} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}} + {{d3}\quad \tan \quad \theta \quad i}} \leq {W2} \leq {{W1} - {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}} - {{d3}\quad \tan \quad \theta \quad {o.}}}}\end{matrix}$


6. The optical modulation device according to claim 4, furthercomprising an air layer having a thickness d3 formed between said firstlight-transmissive substrate and said third light-transmissivesubstrate, said second light-shielding portion being formed on saidsecond surface of said first light-transmissive substrate, and arelationship among Wp, W1, W1′, W2, and W2′ is expressed by equations:$\begin{matrix}{{{W2}^{\prime} + {\left( {{dp}^{\prime} + {d3}} \right)\tan \quad \theta \quad i} + {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W2} - {\left( {{dp}^{\prime} + {d3}} \right)\tan \quad \theta \quad o} - {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}}}} \\{{{W1}^{\prime} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {W2} \leq {{W1} - {{d1}\quad {\frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}.}}}}\end{matrix}$


7. A projector comprising: a light source; an optical modulation deviceaccording to claim 1, and a projection lens for projecting lightmodulated by said optical modulation device.
 8. The projector accordingto claim 7, wherein a relationship among Wp, W1, and W1′ is expressed byan equation:${{W1}^{\prime} + {{dp}\quad \tan \quad \theta \quad i} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W1} - {{dp}\quad \tan \quad \theta \quad o} - {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}}}$

θi being an incident angle of incident light that is incident from theinside of the inner peripheral edge of said cover portion, θo being anincident angle of incident light, that is incident from outside of theinner peripheral edge of said cover portion, dp is a distance from theinner peripheral edge of said cover portion to said second surface ofsaid first light-transmissive substrate, d1 is a thickness of said firstlight-transmissive substrate, W1′ is a distance from the end of saidfirst light-transmissive substrate to an outer peripheral edge of saidfirst light-shielding portion, and n1 is a refractive index of saidfirst light-transmissive substrate.
 9. The projector according to claim8, further comprising a second light-shielding portion formed betweensaid third light-transmissive substrate and said firstlight-transmissive substrate, and a relationship among Wp, W1, and W2 isexpressed by an equation: Wp<W2<W 1 where W2 is a distance from the endof said first light-transmissive substrate to an inner peripheral edgeof said second light-shielding portion.
 10. The projector according toclaim 10, a relationship among Wp, W1, W1′, W2, and W2′ being expressedby equations: $\begin{matrix}{{{W2}^{\prime} + {{dp}^{\prime}\tan \quad \theta \quad i} + {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W2} - {{dp}^{\prime}\tan \quad \theta \quad o} - {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}}}} \\{{{W1}^{\prime} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {W2} \leq {{W1} - {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}}}}\end{matrix}$

W2′ being the distance from the end of said first light-transmissivesubstrate to an outer peripheral edge of said second light-shieldingportion.
 11. The projector according to claim 10, further comprising anair layer having a thickness d3 formed between said firstlight-transmissive substrate and said third light-transmissivesubstrate, said second light-shielding portion being formed on alight-emitting surface of said third light-transmissive substrate, and arelationship among Wp, W1, W1′, W2, and W2′ is expressed by equations:$\begin{matrix}{{{W2}^{\prime} + {{dp}^{\prime}\tan \quad \theta \quad i} + {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W2} - {{dp}^{\prime}\tan \quad \theta \quad o} - {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}}}} \\{{{W1}^{\prime} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}} + {{d3}\quad \tan \quad \theta \quad i}} \leq {W2} \leq {{W1} - {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}} - {{d3}\quad \tan \quad \theta \quad {o.}}}}\end{matrix}$


12. The projector according to claim 10, further comprising an air layerhaving a thickness d3 formed between said first light-transmissivesubstrate and said third light-transmissive substrate, said secondlight-shielding portion being formed on said second surface of saidfirst light-transmissive substrate, and a relationship among Wp, W1,W1′, W2, and W2′ is expressed by equations: $\begin{matrix}{{{W2}^{\prime} + {\left( {{dp}^{\prime} + {d3}} \right)\tan \quad \theta \quad i} + {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {Wp} \leq {{W2} - {\left( {{dp}^{\prime} + {d3}} \right)\tan \quad \theta \quad o} - {{d2}\quad \frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n2}^{2} - {\sin^{2}\theta \quad o}}}}}} \\{{{W1}^{\prime} + {{d1}\quad \frac{\begin{matrix}{\sin \quad \theta \quad i}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad i}}}}} \leq {W2} \leq {{W1} - {{d1}\quad {\frac{\begin{matrix}{\sin \quad \theta \quad o}\end{matrix}}{\sqrt{{n1}^{2} - {\sin^{2}\theta \quad o}}}.}}}}\end{matrix}$